1. Field of Invention
This invention relates to a security device intended to be used between any remote data access device and the public switched telephone network. The security device may be used with a private automatic branch exchange or central office switching system by coupling to a remote programming and maintenance port and particularly to dial up computer connections.
In normal applications the security device is connected betwen a telephone network and telephone loop and a modulator-demodulator (modem) coupled to local automatic dial-up terminal equipment.
There exists a potentially acute problem with respect to security of data bases which are coupled to public telephone lines through automatic dial-up equipment. Under normal circumstances the only security is by means of access codes and user identification codes. The security access codes can be deciphered with relative ease in many instances by use of a computer to test for a correct code. Once the correct code has been identified, the security of a data base can be breached, allowing unauthorized access.
What is therefore needed is a device for enhancing the security of data bases accessible by public telephone lines.
2. Description of the Prior Art
A device known as a service observing unit is manufactured by Teltone Corporation of Kirkland, Washington. The device utilizes a dial back technique for secure access to a data base. The device, however, requires the use of two telephone lines for normal operation, namely an incoming line for connection of the originating call and a second line which is used for the outgoing call back to the calling party.
A number of automatic dialing devices are known to the art. Such devices are normally used for automatic calling operations, for remote billing equipment and for computer to computer data transfers.